Communication unit, system and method for saving power therein

ABSTRACT

A communication unit comprises a receiver for receiving a message sent on an allocation channel, packet identifying logic, capable of identifying a data type of the received message, operably coupled to buffer logic for buffering data packets to be sent to the second communication unit. In an active mode of operation, the receiver of the communication unit is capable of intermittently receiving the message sent on the allocation channel and transition to continuously receive the message sent on the allocation channel in response to either: the buffer logic identifying that data packets are to be transferred to the second communication unit; or the packet identifying logic receiving a communication resource allocation message and identifying resource allocation data therein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and is based upon and claims thebenefit of priority under 35 U.S.C. §120 for U.S. Ser. No. 11/796,007,filed Apr. 25, 2007 (now U.S. Pat. No. 8,072,930), the entire contentsof which is incorporated herein by reference.

FIELD OF THE INVENTION

The field of the invention generally relates to utilization ofcommunication resources in cellular communication systems. Inparticular, but not exclusively, the invention relates to an apparatusand method for power saving in packet switch cellular communicationsystems.

BACKGROUND OF THE INVENTION

Currently, 3rd generation cellular communication systems are beingrolled out to further enhance the communication services provided tomobile phone users. The most widely adopted 3rd generation communicationsystems are based on Code Division Multiple Access (CDMA) and FrequencyDivision Duplex (FDD) or Time Division Duplex (TDD) technology.

TDD provides for the same carrier frequency to be used for both uplinktransmissions, i.e. transmissions from the mobile wireless communicationunit (often referred to as wireless subscriber communication unit) tothe communication infrastructure via a wireless serving base station aswell as downlink transmissions, i.e. transmissions from thecommunication infrastructure to the mobile wireless communication unitvia a serving base station. In TDD, the carrier frequency is subdividedin the time domain into a series of timeslots. The single carrierfrequency is assigned to uplink transmissions during some timeslots andto downlink transmissions during other timeslots. An example of acommunication system using this principle is the Universal MobileTelecommunication System (UMTS). Further description of CDMA, andspecifically of the Wideband CDMA (WCDMA) mode of UMTS, can be found in‘WCDMA for UMTS’, Harri Holma (editor), Antti Toskala (Editor), Wiley &Sons, 2001, ISBN 0471486876.

In order to provide enhanced communication services, the 3rd generationcellular communication systems are designed to support a variety ofdifferent and enhanced services. One such enhanced service is multimediaservices. The demand for multimedia services that can be received viamobile phones and other handheld devices is set to grow rapidly over thenext few years. Multimedia services, due to the nature of the datacontent that is to be communicated, require a high bandwidth. Hence,packet-switched based data provision is generally adopted.

Typically, subscriber units (referred to as User Equipment (UE) in 3GPPparlance) that are operationally inactive are placed in a ‘paging’state. In this ‘paging’ state UEs very occasionally listen (possiblyless frequently than 500 msec's) to a dedicated paging channel, whichcarries messages that indicate whether there is downlink (DL) data forthe UE. If the message indicates that DL data exists for the UE, the UEknows that it should transition into an operational state, such as a‘data traffic’ state, where it can send and receive data traffic. Ifthere is UL traffic to be sent to the network, then the UE transitionsstraight away into the appropriate state to send data traffic. However,it is known that this state transition can take a substantial period oftime (typically the state transition can be in the order of 100 msec).

The paging channel is deliberately designed so that the UE only has to‘infrequently’ access it to receive messages, in order to minimise thepower requirements of the UE. However, in accessing the paging channelinfrequently, thereby saving power, there is a consequent increase inlatency in subsequently transmitting or receiving data. In a packetswitched based cellular communication system this latency may beseverely detrimental to the overall performance of the system.

Once the UE has been successfully paged, and is in the ‘data traffic’state, the UEs listens, in every frame, to an allocation channel thatallocates resources on a separate shared channel for a limited period oftime.

The allocation of shared resources may be performed either in responseto the UE signaling to the network that it has uplink (UL) bufferoccupancy, i.e. the UE has buffered data that it needs to transmit tothe network on an uplink channel, or through provision of internalreporting within the network in the case of downlink (DL) data.Supporting UE signaling and/or internal reporting of DL data addsfurther complexity to the system.

It would of course be possible to keep as many users in the ‘datatraffic state’ as possible even though they had not sent or receiveddata for a long period of time. This would minimise latency. However, itwould be detrimental to power requirements at the UE because it wouldhave to listen to the allocation channel in every frame.

It is shown, therefore, that there is trade-off between minimizing UEpower requirements and latency performance.

Subsequently, in the ‘data traffic’ state, all UEs listen, in everyframe, to an allocation channel that allocates shared resources for alimited period of time. Thus, the requirement for all UEs to listen inevery frame to an allocation channel, before transitioning to anallocated channel from a plurality of shared resources, as instructed bythe network, also increases the latency.

Consequently, current techniques are suboptimal. Hence, an improvedmechanism to address the latency versus power saving problem of inpacket switched cellular communication systems is desired.

SUMMARY OF THE INVENTION

Accordingly, embodiments of invention seek to mitigate, alleviate, oreliminate one or more of the abovementioned disadvantages, singly or inany combination.

According to some embodiments of the invention, a communication unit isprovided comprising a receiver for receiving a message sent on anallocation channel, packet identifying logic capable of identifying adata type of the received message operably coupled to buffer logic forbuffering data packets to be sent to the second communication unit. Inan active mode of operation, the receiver is capable of intermittentlyreceiving the allocation channel (to see if there is a message on theallocation channel allocating shared channel to the UE) and transitionto continuously receive the allocation channel in response to at leastone of: the buffer logic identifying that data packets are to betransferred to the second communication unit; or the packet identifyinglogic receiving a communication resource allocation message andidentifying resource allocation data therein.

According to an optional feature of the invention, the communicationunit is configured to operate in a third Generation Partnership Project(3GPP) cellular communication system. Thus, the inventive concept may beapplied to UE states where the UE sends and receives data on sharedchannels.

According to some embodiments of the invention, the packet identifyinglogic may identify whether only a ‘keep alive’ message is contained inthe message sent on the shared channel. In this regard, upon determininga message other than a ‘keep alive’ message, the communication unit maytransition to continuously receive messages that allocate shared channelresources sent on the allocation channel. This optional feature enablesthe communication unit to remain in an inactive sub-state and onlyintermittently listen to the allocation channel whilst receiving ‘keepalive’ messages.

In some embodiments of the invention, the keep alive message may be alink control protocol (LCP) echo/response message when the communicationunit is in the inactive state.

In some embodiments of the invention, the communication unit is awireless subscriber communication unit and the second communication unitis a network-based communication unit. The wireless subscribercommunication unit may comprise buffer determining logic operablycoupled to the buffer logic operable for at least one uplink radio linkcontrol (RLC) buffer(s) and capable of identifying buffer occupancy inthe at least one uplink RLC buffer(s).

In some embodiments of the invention, the communication unit is anetwork-based communication unit and the second communication unit is awireless subscriber communication unit. The network-based communicationunit may comprise buffer determining logic operably coupled to thebuffer logic configured as at least one uplink radio link control (RLC)buffer(s) and capable of identifying buffer occupancy in at least oneof: at least one uplink radio link control (RLC) buffer(s); at least onedownlink RLC buffer(s).

Embodiments of the invention may allow power saving within thecommunication unit, compared to conventional data traffic stateoperation, by facilitating an intermittent and more intelligentlistening operation of the allocation channel. In this manner, asignificant conservation in the battery life of the wireless subscribercommunication unit may be achieved.

Embodiments of the invention may improve latency compared toconventional systems where UEs are placed in a paging state.

Further, some embodiments of the invention may improve the power usagefor UEs that are forced to remain in a ‘data active’ state. In thisregard, some embodiments of the invention may provide an optimalcompromise between these two strategies. Within some embodiments of theinvention it may be possible to vary the frequency that UEs listen tothe allocation channel, and thus provide a gradual transition betweengood latency performance (where the UE reads the allocation frequently)and improved power saving at the UE (where the UE reads allocation lessfrequently).

According to some embodiments of the invention, there is provided amethod of saving power in a cellular communication unit comprising:receiving a message sent on an allocation channel of a cellularcommunication system; identifying a data type of the received messagesent between the cellular communication unit and a second communicationunit; and buffering data packets to be sent to the second communicationunit. The method further comprises: intermittently receiving the messagesent on the allocation channel; and transitioning to continuouslyreceive the message sent on the allocation channel in response toeither: identifying that data packets are to be transferred to thesecond communication unit; or receiving a communication resourceallocation message and identifying resource allocation data therein.

According to other embodiments of the invention, there is provided acommunication unit capable of transferring data packets with a secondcommunication unit. The communication unit comprises a memory; aprocessor coupled to the memory; and program code executable on theprocessor, the program code operable for performing the aforementionedmethod.

According to embodiments of the invention, there is provided a computerprogram product comprising program code for supporting communicationbetween a communication unit and a second communication unit. Thecomputer program product comprises program code for performing theaforementioned method.

According to some embodiments of the invention, there, is provided acommunication unit comprising logic for receiving a message sent on anallocation channel of a cellular communication system; logic foridentifying a data type of the received message sent between thecommunication unit and a second communication unit; and logic forbuffering data packets to be sent to the second communication unit. Thecommunication unit further comprises logic for intermittently receivingthe message sent on the allocation channel; and logic for transitioningto continuously receive the message sent on the allocation channel inresponse to at least one of: logic for identifying that data packets areto be transferred to the second communication unit; logic for receivinga communication resource allocation message and identifying resourceallocation data therein.

According to some embodiments of the invention, there is provided acellular communication system supporting communication between acommunication unit and a second communication unit. The communicationunit comprises a receiver capable of receiving a message sent on anallocation channel of the cellular communication system, packetidentifying logic capable of identifying a data type of the receivedmessage operably coupled to buffer logic for buffering data packets tobe sent to the second communication unit. In an active mode ofoperation, the receiver of the communication unit is capable ofintermittently receiving the message sent on the allocation channel andthe communication unit is capable of transitioning to continuouslyreceive the message sent on the allocation channel in response to atleast one of: the buffer logic identifying that data packets are to betransferred to the second communication unit; the packet identifyinglogic receiving a communication resource allocation message andidentifying resource allocation data therein.

These and other aspects, features and advantages of the invention willbe apparent from, and elucidated with reference to, the embodiment(s)described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 illustrates a communication protocol representation of a cellularcommunication system adapted in accordance with some embodiments of thepresent invention.

FIG. 2 illustrates a protocol-based architecture of a UE sub-statedetermination process in a data traffic state in accordance with someembodiments of the invention.

FIG. 3 illustrates a simplified block diagram of a user equipment (UE)adapted in accordance with some embodiments of the invention.

FIG. 4 illustrates a UE state diagram in accordance with someembodiments of the invention.

FIG. 5 illustrates a network-side state diagram in accordance with someembodiments of the invention.

FIG. 6 illustrates a timing frame format adapted in accordance with someembodiments of the invention.

FIG. 7 illustrates a typical computing system that may be employed toimplement processing functionality in embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The following description focuses on embodiments of the inventionapplicable to a UMTS. (Universal Mobile Telecommunication System)cellular communication system and in particular to a UMTS TerrestrialRadio Access Network (UTRAN) within a 3rd generation partnership project(3GPP) system. However, it will be appreciated that the invention is notlimited to this particular cellular communication system, but may beapplied to other packet switched communication systems.

In embodiments of the invention, a cell_FACH (Forward Access CHannel)state in a 3GPP communication system is adapted to support efficientpower saving, although the inventive concept may be applied to anycommunication system employing shared channels. Cell_FACH state is astate in the current 3GPP standard that may employ a shared channel onlyoperation. For example, an embodiment of the invention may be applied tothe long-term evolution (LTE) standard within 3GPP, where the UE employsshared channels as it is not allocated dedicated resources.

In some embodiments of the invention, when the UE is configured to onlyinfrequently read the allocation channel (for example it is configuredto be in an ‘inactive sub-state’) the UE is able to reduce its powerrequirements by switching off layer-1 and transport channel processingfunctionality during times where the UE knows there is no allocation forit. The layer-1 functionality may also include automatic gain control(AGC), automatic frequency control (AFC) and frame tracking.

Conventionally, a UE transitions into the data traffic state, inresponse to the UE signaling to the network indicating it has UL bufferoccupancy, or by provision of internal reports in the network in thecase of DL data. In contrast to the conventional mechanism, where a UEthen listens in every frame to an allocation channel that allocatesshared resources for a limited period of time, embodiments of theinvention propose a scheme whereby UEs only occasionally listen to theallocation channel while remaining in the data traffic state. Thus,embodiments of the invention provide a ‘sub-state’ within the datatraffic state, hereafter termed an ‘inactive sub-state’.

In an enhanced embodiment of the invention, logic is provided to ensurethat if only higher layer ‘keep alive’ messages (e.g. LCP echo/responsemessages) are sent between the radio network controller (RNC) in theUTRAN and the UE, then the UE remains in the ‘inactive’ state.

The ‘keep-alive’ type messages occur in data networks and are associatedwith protocols that are not directly accessible to users. These messagesare small messages that occur even when there is no data being presentedto the user. They are typically used for establishing, configuring ortesting the data link connection.

Within 3GPP, point-to-point protocol (PPP) provides a method forencapsulating and transporting many different protocol datagrams overpoint-to-point links. It includes a link control protocol (LCP) tomanage the link. Within the LCP protocol there exists an ‘echo-request’and ‘echo-response’ message. In many applications the echorequest/response message is used periodically to confirm that a clientis still connected (hence the term ‘keep alive’) and/or determine roundtrip times.

Other management protocols such as Internet control message protocol(ICMP), which can use IP directly rather than using PPP, have similar‘ping’ functions. These may also be termed ‘keep alive’ messages in thecontext of embodiments of the invention.

Referring now to FIG. 1, a communication protocol representation of acellular-based communication system 100 is shown in outline, inaccordance with embodiments of the invention. In these embodiments, thecellular-based communication system 100 is compliant with, and containsnetwork elements for operating over, a universal mobiletelecommunication system (UMTS) air-interface. In particular, theembodiments relate to the Third Generation Partnership Project (3GPP)specification for wide-band code-division multiple access (WCDMA),time-division code-division multiple access (TD-CDMA) and time-divisionsynchronous code-division multiple access (TD-SCDMA) standard relatingto the UTRAN radio Interface (described in the 3GPP TS 25.xxx series ofspecifications).

In particular, the communication protocol representation 100 of the 3GPPsystem is adapted to support future evolutions of UTRA 3GPP (currentlyreferred to as ‘long term evolution’ (LTE)). The communication protocolrepresentation 100 comprises enhanced Node-Bs (eNBs) 120 communicatingvia an access gateway 105 to other communication entities (not shown)within the communication system.

The access gateway 105 comprises a user plane entity (UPE) 110 operablycoupled to a mobility management entity (MME) 115. The RNC functionalityin LTE resides entirely in the eNode-B. In the access gateway themobility management entity (MME) functionality is mobility functionalityfor paging/idle mode mobility, and the UPE provides user planefunctionality.

As mentioned above, the access gateway 105 is operably coupled to eNBs120, which comprise logic to facilitate communication between thefollowing protocol layers: PDCP 125, radio link control (RLC) layer 130,medium access control (135) layer and the physical (layer-1) layer 145,the communication between these layers being controlled by radioresource control logic 140.

In accordance with embodiments of the invention, the PDCP layer 125 maybe modified to be able to identify ‘keep alive’ type messages. Newsignaling is also provided between the PDCP entity and the radioresource control (RRC) entity 140, so that the RRC entity 140 can beinformed whether data that is, or is not, a keep alive has beendetected. The RRC entity 140 may also modified so that it is able tostore a record of those UEs that are in an ‘inactive’ or an ‘active’sub-state. In this manner, the RRC entity 140 is able to ensure thatwhen messages are sent on the allocation channel (allocating sharedchannel resources) they are sent in an appropriate frame so that aparticular UE in the ‘inactive’ sub-state is reading the allocationchannel in this frame.

In accordance with embodiments of the invention, the radio resourcecontrol (RRC) logic 140 within a network element, such as an enhancedNode-B 120 (or other element such as the radio network control (RNC)element), is adapted to identify a data packet type. For example, in a3GPP context, this may be achieved by identifying a LCP echo/responsemessage at the packet data control protocol (PDCP) layer 125.

Referring now to FIG. 2, a protocol-based architecture 200 of how todetermine a UE sub-state in a data traffic state, which applies equallyto a network and a UE, is illustrated, in accordance with someembodiments of the invention. In the protocol-based architecture 200,user plane data 205 is passed to adapted PDCP logic 210, which inspectsthe received user plane data packets for ‘keep alive’ messages. If theadapted PDCP logic 210 determines that no ‘keep alive’ messages in theuser plane data 205 were received, then the user plane data 205 ispassed through the various layers of the OSI protocol, as in the knownprior art, namely the radio link control layer (RLC) 215, the mediumaccess layer (MAC) 220 and layer-1 physical layer 225.

As will be appreciated by one skilled in the art, for UL data the RRCwill receive a request for allocation firstly (when considering theprotocol-based architecture 200 applies to a network side case), andthen the RRC will allocate shared resources (ensuring that if the UE isin the ‘inactive sub-state’ the appropriate frame is used). The datawill then arrive at the layer-1 physical layer 225, passing through, theMAC layer 220 and the RLC layer 215. Only then will the PDCP logic 210(layer) be able to determine if the data is or is not a ‘keep alive’.

However, in accordance with embodiments of the invention, if the adaptedPDCP logic 210 determines that ‘keep alive’ messages in the user planedata 205 were received, then an indication 230 of this fact is sent toRRC logic 235. In response to this indication, the RRC logic 235configures, using one or more control signal(s) 245, the MAC layer logic220 and the layer-1 logic 225 according to the RRC state. The one ormore control signals ensure that, at the UE side, then the Layer-1functionality can be switched off during times when the UE does not haveto listen to the allocation channel. Also, if HSDPA or enhanced uplinksignaling channel (E-USCH) or LTE is employed, then the MAC layer logic220 is informed when it must read the allocation channel.

At the UTRAN side, if HSDPA/E-USCH in 3GPP or LTE is employed, then theMAC layer logic 220 needs to be informed that the UE is in the inactivesubstate, so that it can ensure that allocation messages are only sentto the UE during frames that it is actually listening to.

The control plane data 240 is then output from the RRC logic 235 throughthe OSI protocol layers: radio link control layer (RLC) 215,re-configured medium access layer (MAC) 220 and re-configured layer-1physical layer 225.

In alternative embodiments of the invention, the adaptation of the MAClayer 220 and/or layer-1 logic 225 may be performed directly in responseto packet identifying logic contained within the network, in contrast toadaptation controlled by the RRC logic. This is the case where LTE orHSDPA/E_USCH is employed, where the RRC really does not need to know thestate because it no longer controls the allocation of shared resources.

One skilled in the art will appreciate that the above logic andcorresponding operational steps has mirrored logic and functionality inthe network, and is shown with respect to the UE for clarity purposes.In this manner, the UE and network are synchronized in determining thesub-state, for example by employing the exemplary flowcharts shown, asthis will ensure that both the UE and the network are synchronisedimplicitly (without signaling).

However, in an alternative embodiment of the invention, in someinstances it may be acceptable for the UE to declare itself in the‘active sub-state’, while the network still believes the UE to beinactive. This scenario enables the UE to listen to the allocationchannel all the time, but where the network will only send an allocationmessage infrequently. This results in extra latency, but at leastallocation messages are not missed.

Referring now to FIG. 3, a block diagram of a wireless subscribercommunication unit (UE in the context of a 3GPP cellular communicationsystem) is shown, adapted in accordance with some embodiments of theinvention.

The UE 300 contains an antenna 302 coupled to antenna switch 304 thatprovides isolation between receive and transmit chains within the UE300.

The receiver, chain, as known in the art, includes receiver front-endcircuitry 306 (effectively providing reception, filtering andintermediate or base-band frequency conversion). The front-end circuitry306 is serially coupled to a signal processing function 308. An outputfrom the signal processing function 308 is provided to a suitable outputdevice 310. A controller 314 maintains overall subscriber unit control.The controller 314 is also coupled to the receiver front-end circuitry306 and the signal processing function 308 (generally realised by adigital signal processor (DSP)). The controller is also coupled to amemory device 316 that selectively stores operating regimes, such asdecoding/encoding functions, synchronisation patterns, code sequences,direction of arrival of a received signal and the like.

In accordance with embodiments of the invention, the timer 318 comprisesa ‘data traffic state inactive’ timer and is operably coupled to thecontroller 314 to control the timing of operations (transmission orreception of time-dependent signals) within the UE 300.

As regards the transmit chain, this essentially includes an input device320, such as a keypad, coupled in series through transmitter/modulationcircuitry 322 and a power amplifier 324 to the antenna 302. Thetransmitter/modulation circuitry 322 and the power amplifier 324 areoperationally responsive to the controller 314.

The signal processor function 308 in the transmit chain may beimplemented as distinct from the processor in the receive chain.Alternatively, a single processor 308 may be used to implementprocessing of both transmit and receive signals, as shown in FIG. 3.Clearly, the various components within the UE 300 can be realized indiscrete or integrated component form, with an ultimate structuretherefore being an application-specific or design selection.

In accordance with some embodiments of the invention, the signalprocessor 308 has been adapted to comprise buffer determining logic 330operable to identify when the UE 300 has zero buffer occupancy in UL RLCbuffers 332. In response to the UE 300 receiving no allocation messagesthat contain DL resources, the signal processor 308 initiates the ‘datatraffic state inactive’ timer 317. The initial timer value is signalledto the UE. If the ‘data traffic state inactive’ timer 317 expires, thenthe UE will be in a data traffic inactive substate.

In the inactive substate, if at anytime the UE receives an allocationmessage, then it will read the allocation channel in every frame untilan update from the packet identifying logic 334 is received.

If the update from the packet identifying logic 334 indicates that theUE 300 should remain in the inactive substate (for example when only‘keep alive’ packets are detected) then radio resource control (RRC)logic 336 will return fully to inactive. substate and read theallocation channel infrequently as defined in the following section.

If the update from the packet identifying logic 334 indicates that theUE 300 should transition to the active state (for example when datapackets other than ‘keep alive’ data packets are detected) then the UE300 will fully enter the active state and read the allocation channel inevery frame.

It should be noted that when in the inactive substate, the UE 300 willcontinue to act on all allocation messages as normal.

Referring now to FIG. 4, a UE state diagram 400 is illustrated inaccordance with some embodiments of the invention. The UE state diagram400 commences in step 405 with the UE in a data traffic ‘inactive’substate. The UE remains in the data traffic ‘inactive’ substate 405while UL ‘keep alive’ data is detected in step 410. If UL non ‘keepalive’ data is detected, in step 445, the data traffic state becomesactive and a data traffic state inactive timer is initiated, in step435.

In accordance with some embodiments of the invention, the data trafficstate inactive timer measures the time since real (for example,non-‘keep alive’) data has been transferred to/from the UE. Wheneverreal (for example, non-‘keep alive’) data is detected, it is reset. Insome embodiments of the invention, the data traffic state inactive timermay have a preconfigured timeout value (signalled to the UE). The UEreturns to the inactive state when the timeout value is reached.

In the inactive substate, if at any time the UE receives an allocationmessage allocating DL resources, then the UE re-configures itself toread the allocation channel in every frame, as shown in step 420, whileDL ‘keep alive’ data is detected in step 425. As soon as DL ‘non-keepalive’ data is detected, in step 430, the data traffic state transitionsfrom an inactive substate to an active state.

A data traffic state inactive timer is initiated when there is zero ULbuffer occupancy and the UE receives no allocation message thatallocates DL shared channel resources, in step 435. Upon determiningthat the UL buffer occupancy is greater than zero, or allocationmessages that allocate DL shared channel resources have been received,the data traffic state inactive timer is reset in step 450.

If there is no UL buffer occupancy or DL allocations the data trafficstate inactive timer is configured to continue running, in step 455. Ifthe data traffic state inactive timer expires, in step 440, the datatraffic state resumes as being inactive, in step 405.

Since there is no signaling from the UE to indicate which substate it isin, it is necessary to mirror the timer functionality described for theUE above, in the network. This is important to ensure that the RNC sendsallocation messages to UEs operating in a data traffic inactive substatethat are actually listening to the allocation channel in that frame.Advantageously, synchronisation is performed by running the same timer(for example using a same expiration time) at the network, and also bylooking at the DL buffer occupancy and buffer occupancy reports providedby the UE and allowing the timer to run when both of these are zero.

The aforementioned functionality provides a modification of the existingPDCP functions by identifying the ‘keep alive’ packets and adaptingMAC-layer and RRC-layer logic to control when the UE looks at theallocator channel in response thereto. For example, in older versions of3GPP it was the RRC layer that controlled the shared channel operation.Hence, in this case, the RRC can be told that the UE needs only look atthe allocator channel infrequently. In later versions of 3GPP (whenenhanced Uplink and HSDPA are used), then the MAC layer is the layerthat controls and receives allocation information. Hence, this controltells the appropriate entity, either the MAC logic entity or the RRClogic entity to look at the allocator channel infrequently. For example,once every 16 frames.

Referring now to FIG. 5, a network-side state diagram 500 is illustratedin accordance with some embodiments of the invention. In someembodiments of the invention, for example, in a non-LTE implementation,the network-side state diagram 500 may be employed in the RNC, whichwill be used hereafter. The RNC operation commences when the RNC haszero RLC buffer occupancy in DL and UL for a particular UE. The RNC mayrecognize that there is no UL buffer occupancy, based on reports fromthe UE, rather than direct inspection of the buffers. Here, the RNCstarts the ‘data traffic state inactive (RNC)’ timer for that UE, asshown in step 505. Whilst the UE is still in the inactive substate, theRRC logic will act upon requests for allocation messages from the UE asnormal, where the allocations are made in the appropriate frame. Normaloperation in the context of embodiments of the present invention iswhere the buffer occupancy is reported to the allocator/scheduler logic(either in the MAC layer or the RRC/RNC logic) and resources areallocated. However, if the UE is in the inactive substate, then theallocation message is sent during a frame when the UE is listening.

The RNC remains in the data traffic ‘inactive’ substate 505 while DLbuffer occupancy or an allocation request message is received, forexample thereby indicating that ‘keep alive’ data is detected in step510.

If at anytime a request for allocation is received at the RNC, then thiswill be acted on in the normal manner and the UE will stay in theinactive substate. Only if the packet identifying logic subsequentlyindicates that non ‘keep alive’ data is present in a received allocationrequest message, in step 515, will the UE be declared to be in an activedata traffic state as shown in step 520. Alternatively, if the packetidentifying logic declares that the data is only ‘keep alive’ data, thenthe UE will stay in the inactive substate, looping as shown in step 510.

While the UE is operating in the inactive substate, then at any timewhere the DL RLC buffer occupancy is greater than zero, for example theDL buffer occupancy comprises ‘non-keep alive’ data, in step 530, andthe RRC allocates resources to this UE, then the RRC logic transmits anallocation message to the UE. This allocation message will request thatthe UE confirm receipt of this message, as well as allocating resourcesto the UE. The RNC then waits for the UE to transmit a confirmallocation message in step 535. Upon receipt of the confirm allocationmessage received from the UE in step 540, the data traffic state becomesactive in step 520.

If the RNC UL or DL buffer occupancy is detected, the ‘data trafficstate inactive’ timer is reset, as shown in step 545. In contrast, ifthe RNC detects no UL or DL buffer occupancy, the ‘data traffic stateinactive’ timer remains running, as shown in step 550.

If the data traffic state inactive timer expires, in step 525, then theUE will be considered to be in the data traffic inactive substate, instep 505.

Thus, the aforementioned functionality and state transition operationsprovides a modification of the existing PDCP functions by identifyingthe ‘keep alive’ packets and adapting MAC-layer and RRC-layer logic toallow the scheduler to know when UEs will be monitoring the allocatorchannel in response thereto. Here, the scheduler may be the standard‘request and allocate’ scheduler in 3GPP, where buffer volumes are inputand resources are allocated to the UE as output. Simple round robinschemes may be employed or more complex techniques employed, such asweighted fair queuing.

Referring now to FIG. 6, a timing frame format 600 illustrates oneembodiment of how frames are determined for those UEs, which areoperating in an inactive substate, for them to be able to read theallocation channel.

The allocation channel may be either expressly signalled to the UE inthe initial setup message (typically in the radio bearer setup messagein a 3GPP context) or via a predefined mapping based on the UEsidentifier such as:

(UE_identifier mod repetition_period)=Frame_number modrepetition_period.

In both cases the frame at which the UE listens to the allocationchannel is known to both the UE and network sides, as the UEs areallocated a particular frame in which they listen to the allocationchannel. For example, as illustrated in FIG. 6, the UE may be instructedto listen to the allocation channel in the frames that the UEidentifies, such as frame number 16=‘2’ 615 and frame number 16=‘10’620. A typical repetition_period 610 would be 16 frames or 32 frames.

Although the aforementioned embodiment is described with reference toonly listening to two frames from sixteen frames, any number ofinfrequently read frames versus non-read frames may be used, dependentupon the desired application. For example, for applications where powersaving is a key requirement, the UE may be configured to moreinfrequently read the allocation frames, e.g. read a single allocatedframe every 32 or 64 frames. Alternatively, if minimising latency is akey driver in the chosen application, then reading alternative framesor, for example, a frame every three frames may be employed.

In some embodiments of the invention, the decision on the infrequencyrate may be dynamically and autonomously adjusted by a controller (saycontroller 314 in FIG. 3) based on the application being performed.

Since the UE now reads the allocation channel infrequently, the networkmust delay any allocation of radio resources to the UE (in response to aDL buffer occupancy indication) until the network (e.g. an RNC in oneembodiment of the invention) knows that the UE will read the allocationchannel. Therefore, as will be appreciated by one skilled in the art,there is a slight increase in latency associated with inactive sub-stateUEs. This is due to the infrequent listening to the allocator channel bythe UE. The period of the listening is controlled by the signaling fromthe network. However, the latency here is significantly less than theknown conventional approach of placing the UE in the paging state. In apaging state, the UE detects paging indicators, subsequently listens tothe paging channel and extricates itself from the paging state. Thencould an allocation to the UE be made. Thus, the known conventionalapproach of placing the UE in the paging state represents significantlymore latency than is the case with the aforementioned embodiments of theinvention.

In the case of UL data transmission, the UE may immediately send arequest for allocation when UL buffer occupancy is detected at the UE.The UE will then immediately leave the inactive substate, therebyallowing the allocation to be made immediately. Advantageously, there istherefore no latency penalty associated with UL data transmission.

It will be appreciated that, for clarity purposes, the above descriptionhas described embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits or processors, for example with respect to the broadcast modelogic or management logic, may be used without detracting from theinvention. For example, functionality illustrated to be performed byseparate processors or controllers may be performed by the sameprocessor or controller. Hence, references to specific functional unitsare only to be seen as references to suitable means for providing thedescribed functionality, rather than indicative of a strict logical orphysical structure or organization.

Aspects of the invention may be implemented in any suitable formincluding hardware, software, firmware or any combination of these. Theinvention may be implemented, at least partly, as computer softwarerunning on one or more data processors and/or digital signal processors.Thus, the elements and components of an embodiment of the invention maybe physically, functionally and logically implemented in any suitableway. The functionality may be implemented in a single unit, in aplurality of units or as part of other functional units.

Although embodiments of the invention are described in terms of thecell_FACH state in a 3GPP wireless communication system, the inventiveconcept is not restricted to these embodiments. In particular, forexample, embodiments of the invention may be applied to futureevolutions of UTRA 3GPP (currently referred to as ‘long term evolution’(LTE)) or indeed any other ‘state’ based channel resource mechanism forany other wireless communication system.

The aforementioned inventive concept aims to provide at least one ormore of the following advantages:

-   -   (i) Latency associated with UL data transmission is unaffected        compared to conventional data traffic state (therefore        significantly better than for the case where UEs are placed in        paging state).    -   (ii) Latency associated with DL transmission is only marginally        increased compared to conventional data traffic state (therefore        significantly better than for the case where UEs are placed in        paging state).    -   (iii) Significant UE power saving can be achieved compared to        conventional data traffic state operation.    -   (iv) In this manner, a significant conservation in the battery        life of the wireless subscriber communication unit can be        achieved.    -   (v) Power UE power saving is achieved despite the existence of        ‘keep alive’ messages that would ordinarily move the UE to an        ‘active’ state.

While the invention has been described in terms of particularembodiments and illustrative figures, those of ordinary skill in the artwill recognize that the invention is not limited to the embodiments orfigures described. Although embodiments of the present invention aredescribed, in some instances, using UMTS terminology, those skilled inthe art will recognize that such terms are also used in a generic senseherein, and that the present invention is not limited to such systems.

Those skilled in the art will recognize that the operations of thevarious embodiments may be implemented using hardware, software,firmware, or combinations thereof, as appropriate. For example, someprocesses can be carried out using processors or other digital circuitryunder the control of software, firmware, or hard-wired logic. (The term‘logic’ herein refers to fixed hardware, programmable logic and/or anappropriate combination thereof, as would be recognized by one skilledin the art to carry out the recited functions.) Software and, firmwarecan be, stored on computer-readable media. Some other processes can beimplemented using analog circuitry, as is well known to one of ordinaryskill in the art. Additionally, memory or other storage, as well ascommunication components, may be employed in embodiments of theinvention.

FIG. 7 illustrates a typical computing system 700 that may be employedto implement processing functionality in embodiments of the invention.Computing systems of this type may be used in the eNB (in particular,the scheduler of the eNB), core network elements, such as the aGW, andthe UEs, for example. Those skilled in the relevant art will alsorecognize how to implement the invention using other computer systems orarchitectures. Computing system 700 may represent, for example, adesktop, laptop or notebook computer, hand-held computing device (PDA,cell phone, palmtop, etc.), mainframe, server, client, or any other typeof special or general purpose computing device as may be desirable orappropriate for a given application or environment. Computing system 700can include one or more processors, such as a processor 704. Processor704 can be implemented using a general or special purpose processingengine such as, for example, a microprocessor, microcontroller or othercontrol logic. In this example, processor 704 is connected to a bus 702or other communications medium.

Computing system 700 can also include a main memory 708, such as randomaccess memory (RAM) or other dynamic memory, for storing information andinstructions to be executed by processor 704. Main memory 708 also maybe used for storing temporary variables or other intermediateinformation during execution of instructions to be executed by processor704. Computing system 700 may likewise include a read only memory (ROM)or other static storage device coupled to bus 702 for storing staticinformation and instructions for processor 704.

The computing system 700 may also include information storage system710, which may include, for example, a media drive 712 and a removablestorage interface 720. The media drive 712 may include a drive or othermechanism to support fixed or removable storage media, such as a harddisk drive, a floppy disk drive, a magnetic tape drive, an optical diskdrive, a compact disc (CD) or digital video drive (DVD) read or writedrive (R or RW), or other removable or fixed media drive. Storage media718 may include, for example, a hard disk, floppy disk, magnetic tape,optical disk, CD or DVD, or other fixed or removable medium that is readby and written to by media drive 714. As these examples illustrate, thestorage media 718 may include a computer-readable storage medium havingstored therein particular computer software or data.

In some embodiments, information storage system 710 may include othersimilar components for allowing computer programs or other instructionsor data to be loaded into computing system 700. Such components-mayinclude, for example, a removable storage unit 722 and an interface 720,such as a program cartridge and cartridge interface, a removable memory(for example, a flash memory or other removable memory module) andmemory slot, and other removable storage units 722 and interfaces 720that allow software and data to be transferred from the removablestorage unit 718 to computing system 700.

Computing system 700 can also include a communications interface 724.Communications interface 724 can be used to allow software and data tobe transferred between computing system 700 and external devices.Examples of communications interface 724 can include a modem, a networkinterface (such as an Ethernet or other NIC card), a communications port(such as for example, a universal serial bus (USB) port), a PCMCIA slotand card, etc. Software and data transferred via communicationsinterface 724 are in the form of signals which can be electronic,electromagnetic, optical or other signals capable of being received bycommunications interface 724. These signals are provided tocommunications interface 724 via a channel 728. This channel 728 maycarry signals and may be implemented using a wireless medium, wire orcable, fiber optics, or other communications medium. Some examples of achannel include a phone line, a cellular phone link, an RF link, anetwork interface, a local or wide area network, and othercommunications channels.

In this document, the terms ‘computer program product’‘computer-readable medium’ and the like may be used generally to referto media such as, for example, memory 708, storage device 718, orstorage unit 722. These and other forms of computer-readable media maystore one or more instructions for use by processor 704, to cause theprocessor to perform specified operations. Such instructions, generallyreferred to as ‘computer program code’ (which may be grouped in the formof computer programs or other groupings), when executed, enable thecomputing system 700 to perform functions of embodiments of the presentinvention. Note that the code may directly cause the processor toperform specified operations, be compiled to do so, and/or be combinedwith other software, hardware, and/or firmware elements (e.g., librariesfor performing standard functions) to do so.

In an embodiment where the elements are implemented using software, thesoftware may be stored in a computer-readable medium and loaded intocomputing system 700 using, for example, removable storage drive 714,drive 712 or communications interface 724. The control logic (in thisexample, software instructions or computer program code), when executedby the processor 704, causes the processor 704 to perform the functionsof the invention as described herein.

It will be appreciated that, for clarity purposes, the above descriptionhas described embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, processors or domains may be used without detracting from theinvention. For example, functionality illustrated to be performed byseparate processors or controllers may be performed by the sameprocessor or controller. Hence, references to specific functional unitsare only to be seen as references to suitable means for providing thedescribed functionality, rather than indicative of a strict logical orphysical structure or organization.

Although the invention has been described in connection with someembodiments, it is not intended to be limited to the specific form setforth herein. Rather, the scope of the present invention is limited onlyby the claims. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognize that various features of the described embodimentsmay be combined in accordance with the invention.

Furthermore, although individually listed, a plurality of means,elements or method steps may be implemented by, for example, a singleunit or processor. Additionally, although individual features may beincluded in different claims, these may possibly be advantageouslycombined, and the inclusion in different claims does not imply that acombination of features is not feasible and/or advantageous. Also, theinclusion of a feature in one category of claims does not imply alimitation to this category, but rather the feature may be equallyapplicable to other claim categories, as appropriate.

Although the invention has been described in connection with someembodiments, it is not intended to be limited to the specific form setforth herein. Rather, the scope of the present invention is limited onlyby the accompanying claims. Additionally, although a feature may appearto be described in connection with particular embodiments, one skilledin the art would recognize that various features of the describedembodiments may be combined in accordance with the invention. In theclaims, the term ‘comprising’ does not exclude the presence of otherelements or steps.

Furthermore, although individually listed, a plurality of means,elements or method steps may be implemented by, for example, a singleunit or processor. Additionally, although individual features may beincluded in different claims, these may possibly be advantageouslycombined, and the inclusion in different claims does not imply that acombination of features is not feasible and/or advantageous. Also, theinclusion of a feature in one category of claims does not imply alimitation to this category, but rather indicates that the feature isequally applicable to other claim categories, as appropriate.

Furthermore, the order of features in the claims does not imply anyspecific order in which the features must be performed and in particularthe order of individual steps in a method claim does not imply that thesteps must be performed in this order. Rather, the steps may beperformed in any suitable order. In addition, singular references do notexclude a plurality. Thus, references to ‘a’, ‘an’, ‘first’, ‘second’,etc. do not preclude a plurality.

1. A communication unit comprising: a receiver that receives a messagesent on an allocation channel; and packet identifying logic capable ofidentifying whether a keep alive message is contained in a receivedcommunication resource allocation message, wherein, in an active mode ofoperation, the receiver is capable of intermittently receiving acommunication resource allocation message sent on the allocation channeland capable of transitioning to continuously receive a subsequentmessage sent on the allocation channel in response to the packetidentifying logic determining a subsequent message other than a keepalive message, wherein the keep alive message is a link control protocol(LCP) echo/response message in the inactive state.
 2. A communicationunit, comprising: a receiver that receives messages sent on anallocation channel; buffer logic configured to buffer data packets to besent to a second communication unit; and buffer determining logicoperably coupled to the buffer logic and that identifies bufferoccupancy in at least one uplink radio link control (RLC) buffer(s),wherein, in an active mode of operation, the receiver is capable ofintermittently receiving a message sent on the allocation channel andcapable of transitioning to continuously receive the message sent on theallocation channel in response to the buffer logic identifying that datapackets are to be transferred to the second communication unit.
 3. Acommunication unit, comprising: a receiver that receives a message senton an allocation channel; buffer logic configured to buffer data packetsto be sent to a second communication unit; buffer determining logicoperably coupled to the buffer logic operable to identify for bufferoccupancy in at least one of: at least one uplink radio link control(RLC) buffer(s); and at least one downlink radio link control (RLC)buffer(s), wherein, in an active mode of operation, the receiver iscapable of intermittently receiving a message sent on the allocationchannel and capable of transitioning to continuously receive the messagesent on the allocation channel in response to the buffer logicidentifying that data packets are to be transferred to the secondcommunication unit.
 4. A method of saving power in a cellularcommunication unit comprising: receiving messages sent on an allocationchannel of a cellular communication system; identifying whether a keepalive message is contained in a received communication resourceallocation message; intermittently receiving the messages sent on theallocation channel; and transitioning to continuously receive themessage sent on the allocation channel in response to determining amessage other than the keep alive message, wherein the keep alivemessage is a link control protocol (LCP) echo/response message in aninactive state.
 5. A method of saving power in a cellular communicationunit comprising: receiving messages sent on an allocation channel of acellular communication system; buffering data packets to be sent to asecond communication unit; identifying buffer occupancy in at least oneuplink radio link control (RLC) buffer(s); intermittently receiving themessages sent on the allocation channel; and transitioning tocontinuously receive the message sent on the allocation channel inresponse to identifying that data packets are to be transferred to thesecond communication unit.
 6. A method of saving power in a cellularcommunication unit further comprising: receiving messages sent on anallocation channel of a cellular communication system; buffering datapackets to be sent to a second communication unit; identifying bufferoccupancy in at least of: at least one uplink radio link control (RLC),buffer(s); and at least one downlink radio link control (RLC) buffer(s);intermittently receiving the messages sent on the allocation channel;and transitioning to continuously receive the message sent on theallocation channel in response to identifying that data packets are tobe transferred to the second communication unit.
 7. A non-transitorycomputer readable medium including computer program instructions, whichwhen executed by a communication unit, cause the communication unit toperform a method comprising: receiving messages sent on an allocationchannel of a cellular communication system; identifying whether a keepalive message is contained in a received communication resourceallocation message; intermittently receiving the messages sent on theallocation channel; and transitioning to continuously receive themessage sent on the allocation channel in response to determining amessage other than the keep alive message, wherein the keep alivemessage is a link control protocol (LCP) echo/response message in aninactive state.
 8. A non-transitory computer readable medium includingcomputer program instructions, which when executed by a communicationunit, cause the communication unit to perform a method comprising:receiving messages sent on an allocation channel of a cellularcommunication system; buffering data packets to be sent to a secondcommunication unit; identifying buffer occupancy in at least one uplinkradio link control (RLC) buffer(s); intermittently receiving themessages sent on the allocation channel; and transitioning tocontinuously receive the message sent on the allocation channel inresponse to identifying that data packets are to be transferred to thesecond communication unit.
 9. A non-transitory computer readable mediumincluding computer program instructions, which when executed by acommunication unit, cause the communication unit to perform a methodcomprising: receiving messages sent on an allocation channel of acellular communication system; buffering data packets to be sent to asecond communication unit; identifying buffer occupancy in at least of:at least one uplink radio link control (RLC), buffer(s); and at leastone downlink radio link control (RLC) buffer(s); intermittentlyreceiving the messages sent on the allocation channel; and transitioningto continuously receive the message sent on the allocation channel inresponse to identifying that data packets are to be transferred to thesecond communication unit.
 10. A communication unit comprising: logicfor receiving messages sent on an allocation channel of a cellularcommunication system; logic for identifying whether a keep alive messageis contained in a received communication resource allocation message;logic for intermittently receiving the messages sent on the allocationchannel; and logic for transitioning to continuously receive the messagesent on the allocation channel in response to determining a messageother than the keep alive message, wherein the keep alive message is alink control protocol (LCP) echo/response message in an inactive state.11. A communication unit comprising: logic for receiving messages senton an allocation channel of a cellular communication system; logic forbuffering data packets to be sent to a second communication unit; logicfor identifying buffer occupancy in at least one uplink radio linkcontrol (RLC) buffer(s); logic for intermittently receiving the messagessent on the allocation channel; and logic for transitioning tocontinuously receive the message sent on the allocation channel inresponse to identifying that data packets are to be transferred to thesecond communication unit.
 12. A communication unit comprising: logicfor receiving messages sent on an allocation channel of a cellularcommunication system; logic for buffering data packets to be sent to asecond communication unit; logic for identifying buffer occupancy in atleast of: at least one uplink radio link control (RLC), buffer(s); andat least one downlink radio link control (RLC) buffer(s); logic forintermittently receiving the messages sent on the allocation channel;and logic for transitioning to continuously receive the message sent onthe allocation channel in response to identifying that data packets areto be transferred to the second communication unit.
 13. A cellularcommunication system supporting communication between a communicationunit and a second communication unit, wherein the communication unitcomprises: a receiver that receives a message sent on an allocationchannel; and packet identifying logic capable of identifying whether akeep alive message is contained in a received communication resourceallocation message, wherein, in an active mode of operation, thereceiver is capable of intermittently receiving a communication resourceallocation message sent on the allocation channel and capable oftransitioning to continuously receive a subsequent message sent on theallocation channel in response to the packet identifying logicdetermining a subsequent message other than a keep alive message,wherein the keep alive message is a link control protocol (LCP)echo/response message in the inactive state.
 14. A cellularcommunication system supporting communication between a communicationunit and a second communication unit, wherein the communication unitcomprises: a receiver that receives messages sent on an allocationchannel; buffer logic configured to buffer data packets to be sent tothe second communication unit; and buffer determining logic operablycoupled to the buffer logic and that identifies buffer occupancy in atleast one uplink radio link control (RLC) buffer(s), wherein, in anactive mode of operation, the receiver is capable of intermittentlyreceiving a message sent on the allocation channel and capable oftransitioning to continuously receive the message sent on the allocationchannel in response to the buffer logic identifying that data packetsare to be transferred to the second communication unit.
 15. A cellularcommunication system supporting communication between a communicationunit and a second communication unit, wherein the communication unitcomprises: a receiver that receives a message sent on an allocationchannel; buffer logic configured to buffer data packets to be sent tothe second communication unit; buffer determining logic operably coupledto the buffer logic operable to identify buffer occupancy in at leastone of: at least one uplink radio link control (RLC) buffer(s); and atleast one downlink radio link control (RLC) buffer(s), wherein, in anactive mode of operation, the receiver is capable of intermittentlyreceiving a message sent on the allocation channel and capable oftransitioning to continuously receive the message sent on the allocationchannel in response to the buffer logic identifying that data packetsare to be transferred to the second communication unit.